Looking at your specs, there's no way you should be dipping down to those framerates in any game at any time, if you're playing at 1080p. I mean, you have a 3570K and a GTX670, that's a pretty powerful rig that shouldn't necessitate a PhysX card. There must be something else wrong. What driver version are you running? Are you buy chance playing on three monitors?

Single monitor currently running at 1680x1050 driver are freshly updated (again) to 310.90 - WHQL

also afterburner shows usage only ever getting up to 60-80 % while gaming. Currently at a loss